The IEC 62443 series provides a shared language for cybersecurity in industrial automation and control systems. It does not replace field analysis; it helps make that analysis explicit, traceable, and connected to the system lifecycle.
Begin with the system under consideration
Before drawing a boundary, define the system, its functions, interfaces, and surrounding responsibilities. An unclear boundary quickly produces zones that are too broad or dependencies that remain invisible.
Group assets according to risk
A zone groups assets with coherent security requirements. A conduit describes communication between zones. This makes it possible to distinguish what must be allowed, monitored, limited, or justified instead of treating the entire network the same way.
Connect risk to requirements
IEC 62443-3-2 calls for risk assessment by zone and conduit, a target security level, and documented security requirements. The target level is not a marketing label; it should follow from risk and guide verifiable technical and organizational measures.
Keep the model alive
Zones and conduits need to evolve with migrations, new remote access, supplier changes, and process modifications. Their value comes from use in change reviews, acceptance testing, and lifecycle management — not simply from appearing in a report.